1. Field of the Invention
This invention relates to a new gel useful for cosmetics and foods. It yields an emulsion when mixed with water; this emulsion is useful for cosmetics, medicines and foods.
2. Description of the Prior Art
Diverse gelatinizing agents have been employed in cosmetic, medicine and food industries for forming gels, for controlling viscosity and for improving "feel". Various types of gels, including hydrophilic and lipophilic type gels, are known. Lipophilic gel is prepared by dispersing a lipophilic gelatinizing agent in an oil component; hydrophilic gel is prepared by hydrophilic gelatinizing agents.
Sucrose esters are known nonionic surfactants having a meritorious absence of toxicity (U.S. Pat. No. 2,893,990). The HLB (Hydrophilic Lipophilic Balance) values of sucrose esters range widely from a hydrophilic to a lipophilic region (HLB from about 3 to 18). Lipophilic sucrose esters are used mainly to obtain W/O emulsions. Lipophilic sucrose esters or dextrin higher fatty-acid esters provide safe and nontoxic gelatinizing agents; however, the resultant gels have various disadvantages, e.g. non-homogeneity, poor feel (they are sticky or oily) and lack of water washability. Polar materials which do not dissolve in oil and fat cannot be dissolved in such gels.
On the other hand, industrial use of hydrophilic sucrose esters has been limited by their poor dispersibility in oil and poor emulsifying power.
It is not impossible to prepare an O/W emulsion with hydrophilic sucrose esters provided a larger amount of the esters is used or the aid of an additional emulsifier is resorted to. For instance, from 5 to 30 percent of sucrose is used in U.S. Pat. No. 2,951,015, but from 5 to 40 percent soap is also required to prepare a penicillin emulsion. A further serious disadvantage of such gels is that water-free gels are not available and that a gel containing a large amount of oil is not available.
An oil-in-polyhydric alcohol gel (O/W gel hereinafter) or a reverse type gel (W/O gel hereinafter) are much desired particularly for cosmetics and various purposes.